The class of polymers of carbon monoxide and olefin(s) has been known for a number of years. Brubaker, U.S. Pat. No. 2,495,286 produced such polymers in the presence of free radical catalysts, i.e, peroxy compounds. U.K. No. 1,081,304 produced similar polymers of higher carbon monoxide content in the presence of alkylphosphine complexes of palladium salts as catalyst. Nozaki extended this process through the use of arylphosphine complexes of palladium salts and certain inert solvents, e.g., U.S. Pat. No. 3,694,412.
More recently the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon, e.g., ethylene or ethylene and propylene, has become of greater interest, in part because of the greater availability of these polymers. The polymers have been shown to be of the formula --CO(A)-- where A is the moiety of the unsaturated hydrocarbon polymerized through the ethylenic unsaturation. For example, when the ethylenically unsaturated hydrocarbon is ethylene, the polymer is represented by the formula --CO(--CH.sub.2 --CH.sub.2)--. The general process for the production of such polymers is illustrated by a number of published European patent applications including No. 0,121,965 and No. 0,181,014. The process generally involves a catalyst composition formed from a compound of the Group VIII metals palladium, cobalt or nickel, the anion of a non-hydrohalogenic acid having a pKa below 2 and a bidentate ligand of phosphorus, arsenic or antimony.
The resulting polymers are relatively high molecular weight thermoplastics having utility in the production of shaped articles such as containers for food and drink and parts for the automotive industry. The polymers are characterized by relatively high melting points, generally over 175.degree. C., frequently over 210.degree. C., depending upon the molecular weight and the chemical nature of the polymer. During processing of these polymers, the polymer is often heated to temperatures near or above the melting point and maintained at such temperatures for times which vary with the nature of the thermal processing. Although the polymer is relatively stable at such temperatures, it will undergo some thermal degradation as will many polymers of that general type. The degradation is most easily evidenced by loss of weight on standing at elevated temperatures in air or even in inert gases such as nitrogen. It would be of advantage to provide a polyketone polymer of enhanced thermal stability as evidenced by reduced weight loss when maintained at elevated temperatures. It would also be of advantage to provide a polyketone polymer of enhanced crystallinity and crystallizability.